An attention has been paid to a technology of specifying a position of a terminal at a high precision in an in-house. Specifically, the technology of employing a signal of a wireless LAN (Local Area Network) that is set by an enterprise, a shop, or the like, or the technology of specifying a position employing Bluetooth, RFID (Radio Frequency Identification) etc. is known.
However, specifying a position of the terminal at a high precision by employing a wireless LAN necessitates a capability of receiving a signal being sent from three wireless LAN base stations or more, and as is often the case with the wireless LAN, no design countermeasure is taken and the base stations are installed at a random position, so there is no guarantee that signals being sent from three wireless LAN base stations or more can be received.
In the system of specifying a position of the terminal by employing a transmitter for transmitting micro radio waves such as Bluetooth and RFID, or a transmitter for transmitting infrared rays, the terminal side has a function of receiving the micro radio wave and the infrared-rays. In the case that the terminal has received the micro radio wave or the infrared-rays, the position of the transmitter, which are transmitting its micro radio wave or its infrared-rays, is assumed to be a position of the terminal. Thus, the arrival distance of the micro radio wave or the infrared rays becomes a degree of a positioning precision, and the positioning at a pinpoint becomes possible; however an arrangement of a large number of the transmitters in a wall and a ceiling is necessitated.
The power has to be supplied to the transmitter being arranged in a wall and a ceiling. So as to enable the power to be supplied, as one method, it is thinkable to do a wiring work for the power supply, which aims at supplying a direct-current power for driving the transmitter.
Further, as another method, the method is thinkable of installing an AC-DC converter for each transmitter being installed in a ceiling and a wall, and causing an AC power supply wire already arranged in an installation location of the transmitter to branch, thereby to input the power into the AC-DC converter.